Dava Sobel and the ladies of the Harvard Observatory

If you don’t know the names Williamena Fleming, Antonia Maury, Henrietta Leavitt, Cecilia Payne, and Annie Jump Cannon, you’re not alone. Many people working in astronomy don’t recognize these women who have made enormous contributions to the field.

Dava Sobel talked about her new book The Glass Universe
Dec. 15 at Town Hall Seattle. Photo: Greg Scheiderer.

“They’re making a splash now,” laughed Dava Sobel, author of the new book The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars (Viking, 2016). Sobel talked about the book Thursday night at Town Hall Seattle.

There is an impression that the women who worked at the observatory were trivialized or marginalized, Sobel said that really wasn’t the case.

“They really were well treated, they were given this tremendous responsibility, they made valuable discoveries, and they were well regarded—and some of them even world famous—in their own lifetimes,” Sobel said. She pointed out that Cannon, for example, held a number of honorary degrees, was a member and officer of the American Astronomical Society, and also was an honorary foreign member of the Royal Astronomical Society.
Interestingly enough, even Sobel, whose bailiwick is science history, hadn’t heard of Leavitt until her name came up during an interview for a magazine article she was writing 20 years ago. Her curiosity was piqued, and the seed for The Glass Universe was planted.

Cheap labor

Sobel noted that when Edward Pickering took over as director of the observatory in 1877 there were already a half a dozen women working there, many of them relatives of the resident astronomers. He liked working with the women. They did good work, and they were inexpensive.

“Women cost less,” Sobel said. “This is an old story about women earning less than men for doing the same work.”

But she added that it wasn’t just dollars and cents for Pickering.

“He was very open minded, broad minded, and felt that higher education for women was a good thing even at a time when this was questioned,” Sobel said. “There were people who really thought that college was bad for girls and could affect their ability to have children.”

Pickering recruited alumnae of women’s colleges who studied astronomy, asking them to make observations and contribute their data to the work of the observatory.

“That would be a way to prove to the world that women could make a contribution to science and that their education wasn’t wasted,” Sobel said.

Financial support from women

The observatory was a separate entity and didn’t receive any money from Harvard. Much of the work at the observatory was possible due to significant financial support from women.

Heiress Anna Palmer Draper and her husband, Dr. Henry Draper, had done some of the earliest work on photographing the spectra of stars. Henry Draper was a medical doctor, but he was, according to Sobel, a passionately engaged and inventive amateur astronomer. They built their own observatory and Henry created many of his own instruments for the work on spectra. Unfortunately, Henry got sick and died at the age of 45. Anna eventually donated much of their gear, and a lot of money, to the observatory to continue the work on stellar spectra.

Philanthropist Catherine Wolfe Bruce donated $50,000 to help the observatory set up a telescope in Peru for observing the skies of the southern hemisphere. Data from this instrument informed Leavitt’s work on variable stars.

Major achievements

The contributions by the computers were significant. A few examples noted by Sobel:
Leavitt studied variable stars and discovered that the brightest ones took longer to cycle through their changes, and that the length of the cycle correlated to the true brightness of the star. Knowing this, one can calculate how far away a variable star is based on how bright it appears from Earth.

“This work was fundamental to distance measurements all over the sky,” Sobel said. The discovery, most often called the period-luminosity relation, is more often these days being referred to as “Leavitt’s Law.”

Cannon, a renowned observer, came up with the star classification system still in use today. Fleming first came to the observatory as a maid, but later found astronomical success, too.

“She was the first woman to get a university title at Harvard,” Sobel said. “She was the curator of astronomical photographs.” Her analysis of some ten thousand stars were critical to the publication of the first Henry Draper Catalogue.

Maury, Draper’s niece, studied at Vassar, graduated with honors in astronomy and physics, and went to work at the observatory, where she came up with a system of identifying stars.

Payne was Harvard’s first Ph.D. in astronomy. It was no surprise that a woman earned the top degree first; all of the early graduate students in astronomy were women because the only money the observatory had for the graduate program came through fellowships established for women to study there. Payne studied spectra of stars and found that hydrogen was far more prevalent in stars than any other element. She wrote about her findings in her dissertation, but it was so counterintuitive that it was downplayed. Within a few years, however, her findings were confirmed.

Given the stature of the accomplishments, it seems astounding that these women are not more well known.

“A lot of history gets buried just because there are so many people, so many characters, so much time goes by,” Sobel noted, adding that the women didn’t feel marginalized at the time. “They really loved what they did and were credited for it, but over time I think it has been downplayed.”

They’re making a splash now

There’s been a lot more attention for the women astronomers in recent years. A decade ago George Johnson penned the biography Miss Leavitt’s Stars (W.W. Norton and Company, 2006). A couple of plays have been written about them, including Silent Sky by Laruen Gunderson, which was produced earlier this year in Seattle by Taproot Theatre. You can go back to read our coverage of the play. The 2014 reboot of the television series Cosmos with Neil deGrasse Tyson featured a segment about the computers.

“This got the attention of a lot of young women,” Sobel said. The Harvard women are also featured in the web series Insignificant.

“It’s great fun to see their story being remembered in so many ways. There are even Lego figures,” of Cannon, Leavitt, and Payne, Sobel said. “You know you’ve made it!”

Several other recent books have highlighted the work of women in space and astronomy. Sobel singled out The Rise of the Rocket Girls (Little, Brown and Company, 2016) by Nathalia Holt, a story about the women who made contributions to space science at the NASA Jet Propulsion Lab; and Hidden Figures (William Morrow, 2016) by Margot Lee Shetterly, a look at the African-American women who worked at Langley in the 1940s and ‘50s. Hidden Figures has been made into a feature film that is scheduled to open in theaters in January.

An important story for our times

Sobel said she enjoyed getting to know the personalities of the ladies of the Harvard College Observatory and feels that their story is an important one in the era of fake news and anti-science attitudes.

“All of us need to be telling true stories about science,” Sobel said. “I feel especially good about this one not only because it’s true, but because I hope it will be inspirational to young women to have models like these ladies and to show that women have always been interested in science.”

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More books by Dava Sobel:

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Book review: Sun Moon Earth by Tyler Nordgren

Tyler Nordgren’s new book Sun Moon Earth: The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets (Basic Books, 2016) is a must read for anyone with even the slightest interest in the heavens, or in the total solar eclipse that will sweep across the United States on August 21, 2017. It’s far more than a where-to-go and how-to-see-it tale, although those pointers do show up at the end (don’t stare at the partially eclipsed Sun without proper, certified shielding, folks.) The fun part is the history lesson suggested by the subtitle.

Indeed, total solar eclipses have been happening for millennia, and Nordgren travels the world to examine what ancient cultures made of this unusual phenomenon. The complete blotting out of the Sun was seldom considered a good thing by people who didn’t understand what was really going on. It has only been in very recent times that the total solar eclipse has been embraced as a tourist attraction. Nordgren’s explanations of how scientific thinking developed and helped explain what was happening during eclipses are engaging and fascinating, as are his tales of the science that has only been possible during these rare events.

Nordgren has become an eclipse chaser himself, and I enjoyed his accounts of his travels to view eclipses, especially his trip to the relatively remote Faroe Islands, between Scotland, Iceland, and Norway, for the eclipse of March 20, 2015. The islands are not exactly the world’s leading tourism destination, and yet they were on that day because it was one of the few dry-land locations from which to see that particular eclipse. It was an interesting tale of the lengths to which people will go to get into the path of totality of a solar eclipse, and how the communities within that path prepare and react to the event.

Most people seem to agree that next year’s total solar eclipse will be seen by more people than any other in history. Often times the path of totality mostly passes over water, as it did for the Faroe Islands in 2015. The last time a total solar eclipse crossed the U.S. like this was in June of 1918. The 2017 eclipse will cross a huge land mass with a large population, many opportunities for tourists, and easy access to the path of totality all along the way.

Sun Moon Earth is a delightful read and would be a most welcome gift for anyone on your list with an interest in astronomy. We included it in our recent gift guide for astronomy buffs.

Author Nordgren is a renaissance man of sorts. He’s a professor of physics and astronomy at the University of Redlands. He’s also a photographer and an artist and has done a variety of beautiful travel posters for the eclipse as well as for other tourist spots around the solar system. They’re available on his website and also referenced in our gift guide. He’s done a great deal of work on night sky astronomy programs in National Parks. He’s the author of Stars Above, Earth Below: A Guide to Astronomy in the National Parks (Praxis, 2010) and spoke about the topic at the 2014 annual banquet of the Seattle Astronomical Society. He’ll be in town again to talk about Sun Moon Earth January 14 at Town Hall Seattle. Tickets are $5 and are available online.

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Preserving the stories of Viking

Rachel Tillman has a scrapbook that is out of this world. What started out as a young girl’s effort to save a cool piece of space history has morphed into a project to preserve the artifacts of the iconic Viking program and the stories of the people who made it happen.

Tillman is the founder, executive director, and chief curator of the Viking Mars Missions Education and Preservation Project, a Portland-based nonprofit that has a huge collection of photos, documents and artifacts from the Viking missions and aims to collect oral histories of some 10,000 people who had a hand in the project—the “Vikings,” as Tillman calls them.

Little kid heaven

Her interest in the mission started early.

“My father worked on the Viking mission,” she said. He is James E. Tillman, a professor emeritus of atmospheric sciences at the University of Washington who was a member of the Viking meteorology team.

“He is an explorer; scientists often are explorers,” Tillman said of her father. “He was so engrossed in his work that lived and breathed it. He brought it home at night.”
What he often brought home was the latest problem or design or a new photo from the lander, and he would ask the kids what they thought about it. Rachel ate it up.

One of the more famous photos in planetary exploration history:
the first sent from Viking 1 shortly after it landed on Mars
July 20, 1976. The original is part of the VMMEPP collection.
Photo: NASA/JPL.

“I was interested from the get-go,” she said. Often she would go to her father’s office after school and soak up all of the conversations he and other scientists were having about technical matters. She’d go look it up and figure out the language, and would often make drawings about what she was learning. She made a few trips with her father to the Jet Propulsion Lab in California, and then got to go to Florida for the launches of the Viking spacecraft in 1975.

“We were down there at Cape Canaveral for the launch with Carl Sagan and Gerry Soffen and my dad and the guys from KSC,” she said. “I saw the rocket fly off.”

That’s quite a crowd for a little kid to hang out with. Rachel recalls Sagan as intense and funny, but said Soffen, the chief scientist on the Viking mission, was her hero.

“He was thoughtful, funny, very smart, absolutely wanted to know whatever it was out there to know,” she said. “He was also a magician. I’m a kid, that’s really cool!”

“The makeup of the people of the mission was amazing,” she added: Hard working, dedicated, sacrificing, funny, intelligent, grumpy, passionate—all of those things that a kid really picks up on.”
“I couldn’t have dreamed a better life than I live,” Rachel said.

They were going to melt it down

Viking was in Rachel’s DNA, but her work as a preservationist started almost as an accident.
NASA built three flight-ready Viking landers, but the first two worked and so the third—VL3—was not needed. Several groups and companies fiddled with plans to turn it into a rover, but ultimately nobody had any funding to do anything, so the lander was set aside. Then around 1979 James Tillman was looking for some used filing cabinets and found some interesting items on the NASA surplus list: his own Viking meteorology instrument, and VL3.

They didn’t scrap Viking Lander 3! The lander, owned
by Rachel Tillman, is on exhibit at the Museum of Flight.
 Photo: Greg Scheiderer.

“They were scrapping it,” Rachel said. “They were going to melt it down.”

She immediately said that they had to get it and save it. Her father thought it was a ridiculous idea, but she convinced him to do it anyway because she had a ready purpose for the lander.

“We’re going to put it in my school,” she told him, “and we’re going to teach kids about robotics and about Mars and about science and engineering.”
Rachel now owns the Viking lander VL3, and it actually was at her school for a while. It also was on display for some time in the electrical engineering department at the UW. For the last ten years it has been on loan to the Museum of Flight, where it is a part of the permanent exhibit Space: Exploring the New Frontier.

“That’s how my preserving began, was with the Viking Lander,” Rachel said. Though it started with a great piece of historic hardware, Rachel is now drawn to the human side.

It’s about the people

“My role as a kid who grew up with the mission is to honor the people who did it,” she said. “Everybody. Not just the rock stars.”

The author in front of information boards the Viking Mars
Missions Education and Preservation Project uses at outreach
events. The box my arm is resting on contains James Tillman’s
Mars meteorology instrument. Photo: Rachel Tillman.

“Every Viking represents a child today that may want to do something like what they did,” Rachel added. “They don’t have to be the mission director, they don’t have to be the principal investigator of a science instrument, they don’t even have to be the lead engineer.”
So many other people had important functions from keeping travel schedules to crunching numbers to designing small but important components of the landers.

“All of these people are so critically important to the mission, and 95 percent of them were forgotten,” Rachel said. “That’s my job: preserve the history and the individuals; not just the timeline events, but the people who did them. That’s what this is all about.”

The Viking Mars Missions Education and Preservation Project was founded in 2008, but only really started doing any outreach in the last year. It’s been mostly underground work as Rachel met and interviewed as many of the Vikings as possible. She thought it was important to do some public events this year, the 40th anniversary of the Vikings’ landings on Mars. They held an open event in Denver—the landers were built there by Martin Marietta, which is now Lockheed Martin. NASA also held some events at Langley and at JPL, and the project held three “Science Pub” talks last month through the Oregon Museum of Science and Industry.

The future of VMMEPP

To date the project has run mostly through donations from James and Rachel Tillman, some of the Vikings, and a few others, but in the next year or so they will be doing some more serious fundraising.

“Our plan is to create a trust fund around all of the artifacts of Viking so they can’t be given away or sold,” Rachel said. “As we get new donations they will stay in this trust.”

She said the fund will help with management of the artifacts as well as preservation. Then in the next year or two they plan to issue a request for proposals from institutions and organizations that would like to host the Viking artifacts.

“They’ll have to meet the requirements that we set for care of the artifacts and for creating access to the artifacts for the public, because that’s critically important,” Rachel said.

In the meantime, the project has established an online museum, where you can go page through raw documents from the Viking missions. The project website is a treasure trove of photos and facts and stories about the Viking missions.

Rachel plans an outreach event at the Hillsdale Library in Portland for December 20, but then will probably be mostly invisible for a little while.

“Doing the oral history interviews, creating access, and protecting the artifacts, those our our three really big pushes.”

It’s a fascinating and worthy cause. If you would like to help with the preservation effort, you can donate to the project online through Facebook (through December 13) or Amazon Smile, or simply send a check to:

Viking Mars Missions Education and Preservation Project
5331 SW Macadam #258-504
Portland, OR 97239

Major changes in store at Goldendale Observatory

Big changes are in store at the Goldendale Observatory in Goldendale, Washington. The facility’s telescope, installed in 1973, has already been reconfigured and more improvements are planned. Most of the existing facility, save for the south dome that houses the telescope, will be demolished this winter and replaced with a bigger, more useful observatory that operators hope will be operational in time for the solar eclipse in August.

Troy Carpenter, interpretive specialist at
Goldendale Observatory State Park, spoke
at a recent Rose City Astronomers meeting
about plans for improvements at the
observatory. Photo: Greg Scheiderer.

Troy Carpenter, interpretive specialist at the observatory, talked about the plans at the recent meeting of the Rose City Astronomers in Portland. He said that up until recently the telescope and facility had been virtually unchanged since they opened.

The telescope, originally a 24.5-inch classical Cassegrain built by amateur astronomers from Vancouver, Washington, was reconfigured this summer.

“It is still the same telescope, but it has become a Newtonian,” Carpenter said. “The primary reason this was converted from Cassegrain to Newtonian is because, frankly, a classical Cassegrain telescope is totally inappropriate in Goldendale, Washington.”

The original scope, with an effective focal ratio of f/14.5, had a focal length of more than 9,000 millimeters. For telescopes and cameras, that’s extremely long.

“I would even say excessively long because it means the telescope can only operate at very high orders of magnification,” Carpenter said. That was bad, because the telescope couldn’t really look at large, dim objects like the Andromeda galaxy or Orion nebula. Also the scope required good seeing conditions, and while it’s dark and clear in Goldendale, the seeing at the observatory isn’t typically great. On top of that, the secondary mirror was eight inches wide with a ten-inch baffle that blocked too much light, leading to poor contrast at the eyepiece.

“In short, what we had was a horribly over-magnified image with terrible contrast all the time, and as a result this very impressive-looking telescope became kind of infamous, and not so much famous, for being awful,” Carpenter said. “All of these issues contributed to the decision to convert it to a Newtonian.”

That work, and some other adjustments to the telescope, its mount, and adjustability, were completed in September. Back to a more appropriate 3,050-millimeter focal length, Carpenter said views through the telescope are much better now. An improvement yet to come is replacement of the primary mirror, which has deteriorated over 43 years of use. In addition, the mirror is five inches thick, weighs 200 pounds, and takes four hours to reach thermal equilibrium, which is essential to good viewing.

A replacement is being fashioned by a company in Pennsylvania that has done work for NASA. The new mirror, computer designed and fabricated from inexpensive materials, will be the same width but just two inches thick and will weigh only 35 pounds. It will take just 15 minutes to cool to ambient temperature. They hope to have it in Goldendale and installed within the next few months. Its price tag, with a generous educational discount, is $25,000, and while that may sound like a lot, Carpenter noted a similar-sized mirror made of fused quartz might go for ten times as much, a quarter million.

New observatory

Big changes are in store for the buildings at Goldendale Observatory State Park, too.

Preliminary plans for the new facility
at Goldendale Observatory.

“We’re tearing it down so that a much larger facility can be built in its place,” Carpenter said. Everything except the south dome that houses the telescope will go. The new facility will include a large auditorium for classes and lectures that will seat about 150, interpretive exhibit space, and a rooftop observation deck. The total cost of the improvements, which are being made in several phases, is $5 million, which is being covered by capital funds appropriated by the Washington State Legislature. Demolition is set for this winter and they hope to be operational with the new facility in time for the total solar eclipse on August 21, 2017. While Goldendale won’t be within the path of totality as it was for the 1979 eclipse, the Sun will be about 98 percent obscured at the observatory that day, so it will still be something to look at.

One page detailing the planned improvements is above; you can see more of them in the latest newsletter from Friends of Goldendale Observatory.

Light pollution

While it’s pretty dark in Goldendale, many feel that light pollution has increased in town in recent years. Concerned folks this summer held a Gorge Night Sky Symposium to discuss the situation. (See our recap of the event.) Carpenter raised a few eyebrows in the room, mine included, with his take on the issue.

Goldendale Observatory. Everything but the dome on
the right will be demolished to make way for improved
facilities. Photo: Greg Scheiderer.

“I’m going to surprise you by not being the loudest opponent of the light pollution we have in Goldendale,” he said. He added that he grew up in New York and has lived in Philadelphia, so he knows light pollution.

“I’ve been to places where stars don’t exist,” he said. So while Goldendale has some light pollution, Carpenter noted that they still have great views of lots of faint fuzzies in the dark night sky.

“It’s low on my priority list because it’s a politically charged issue and it makes us very unpopular every time we bring it up,” Carpenter explained. “Our friends group, however, does care very much about light pollution and they do work hard.”

He noted that the town of Goldendale is working on an improved lighting code, and is converting to full cut-off, dimmable LED street light fixtures. Despite some light pollution, Carpenter said it’s still a great place for stargazing.

“You can see the Milky Way from horizon to horizon in Goldendale,” he said, “and that’s a wonderful thing.”

We look forward to a dark, clear future at Goldendale Observatory.

Reaching kids with "The Big Eclipse"

Those who are convinced that the stars do not affect our lives might wish to consider the story of Elaine Cuyler. Up until recently, Cuyler was minding her own business and working as marketing manager for Eola Hills Wine Cellars just west of Salem, Oregon.

“I never dreamed I’d be working on a kids’ book, let along one on eclipses,” Cuyler said. But that’s exactly what happened. When she learned that the total solar eclipse on August 21, 2017 will cross right over the vineyard, she decided an eclipse-viewing event would be a great way to attract visitors to the winery. As she researched the eclipse, it occurred to Cuyler that kids would really enjoy viewing a total solar eclipse.

“There was really no-one else talking to kids about the eclipse at the time,” she said. Out of that realization Orbit Oregon was born, and Cuyler became its chief eclipse officer. She teamed up with Nancy Coffelt, a well-known author and illustrator from Oregon, to create the book The Big Eclipse (Orbit Oregon, 2016).

“Although I had this concept in mind, it’s really Nancy’s drawings that brought it to life,” Cuyler noted. They also created a kids’ activity book; you can read our review of both, posted last month. Cuyler said there are a couple of purposes behind The Big Eclipse.

“First, I thought it was a great opportunity for kids to learn about astronomy and science and see something really cool,” she said. Secondly, she noted that adults often don’t know what’s going on, either. Her mother was a teacher in Portland during the 1979 total solar eclipse; they were told not to look up, and broadcasters ran public service announcements warning of the dangers of looking at the Sun. While it’s true that proper eye protection is needed to look at the partial phase of a solar eclipse, the warnings amounted to a missed opportunity.

“The concept of a solar eclipse is something that a lot of people aren’t familiar with,” Cuyler said. “That’s why there’s a lot of information [in the book] for parents, too, because they need to learn about it just as much as the kids.”

Providing inspiration

Ultimately, though, it all comes back to the kids.

“We felt that as soon as you can get kids interested in science the better,” Cuyler explained. “Maybe they’re not going to want to sit and listen to a lecture, but they do like crafts, they all know about the Sun, the Moon, and the stars. To get kids thinking about the world around them and how it functions, that’s really the start of getting them to think about why the world works the way it does, and you use science to explain that.”

As Cuyler and Coffelt worked on The Big Eclipse their research included talks with astronomers and folks from NASA who looked at their material. They also spoke with many people who had seen total solar eclipses, including one couple who had viewed 15 of them.

Seattle Astronomy writer Greg Scheiderer, Orbit Oregon’s Elaine
Cuyler, and The Big Eclipse. We thought it was fun to get a
selfie in front of a sign that reads “Choose your own adventure.”

“Their feedback was so great because they shared photos with us and video footage, they told us about the different things that happen,” Cuyler said. “Talking with people who’d actually been through these was invaluable.”

They’ve already test-driven the book in school classrooms, and the kids seem to enjoy it, especially the part where they get to create and make a drawing of their own eclipse myths, just as ancient civilizations tried to explain this celestial phenomenon. Cuyler said the kids are creative and funny with their stories. Her own eclipse myth is a little more figurative.

“It would probably be the book completely eclipsing everything else in my life!” she laughed.

It’s a lot of work getting a book out there. The Big Eclipse is available on the Orbit Oregon website (which also features eclipse glasses and viewers) and Amazon.com, and it is being carried by a growing number of retailers. Cuyler is busy trying to get it into libraries, museums, schools, and summer reading programs, too.

What’s next?

As for the future of Orbit Oregon, Cuyler said The Big Eclipse is really all about the 2017 total solar eclipse, so the book sort of expires after next August 21. But she and Coffelt are considering other books, including volumes about solar eclipses in general, astronomy, and other science topics.

“We had so much fun doing this and we met so many great people that we may extend that,” Cuyler said. “Right now, we’re just focused on the eclipse.”

And on the kids. Cuyler hopes The Big Eclipse gets kids, especially girls, interested in science. When you mix in art and literature, you can grab their interest early.

“If you’re looking at science from an art perspective and crafts activities you can really start young,” Cuyler said. “It appeals to kids, and they’re learning while they’re enjoying the little story that they’re reading.”

Out of that story, and out of seeing a total solar eclipse, can come inspiration. They’ve heard many tales of science teachers who started on their career path when they saw an eclipse as a child.

“That’s what we’re going after, those young kids that might be inspired,” Cuyler said. “That’s really our mission, is to get kids to understand what they’re seeing, learn from it, and then be awed by this amazing spectacle.”

“Hopefully a new generation of science teachers will come out of it.”

Resources:

• Orbit Oregon website
• The Big Eclipse shop
• The Big Eclipse on Facebook
• The Big Eclipse on Twitter

Purchases made through links on Seattle Astronomy support our efforts to bring you interesting space and astronomy stories, and we thank you.

Authors pick Titan as solar system's best place for human colony

Mars is and has long been a popular choice for human colonization should we want or need to leave Earth. But Amanda Hendrix and Charles Wohlforth say that if we’re going to go live somewhere else in the solar system, then Saturn’s moon Titan is the best choice.

Hendrix, a planetary scientist who works for the Planetary Science Institute, and Wohlforth, an award-winning science writer, have just come out with a book, Beyond Earth: Our Path to a New Home in the Planets (Pantheon, 2016). They talked about Titan and the book last week at Town Hall Seattle.

Why go?

“The topic really is not just getting to another planet, but living there and staying there self sufficiently forever,” Wohlforth said. The big question to answer, he noted, is why.

“We don’t, as human beings, normally do big expensive things for no reason at all,” Wohlforth said. “That led us to thinking about what would we want on another planet, or what we would be getting away from here on Earth, that would drive us to want to move to another planet.”

While humans have long had a case of wanderlust, Wohlforth said the reasons to colonize another planet go beyond that.

“Environment drives colonization; it has in the past, and we don’t always call it environment,” he said. “We call it overcrowding or we call it wealth seeking, but really in our society economics is how we talk about environment a lot of the time.”

A key to colonization, he said, is having the resources to do it and to keep it going.

“Making colonies requires technology and it also requires wealth and the ability to make money, and in our world that’s often meant that government gives private industry the money to get started,” Wohlforth said. “Colonies need a reason to exist environmentally or economically, they need major government investment to happen, and ultimately they need a way to support themselves without help from home.”

Why Titan

Hendrix said they developed five main criteria they considered when evaluating a place as a possible site for a human colony. It should have an atmosphere, a magnetosphere, manageable temperatures, a decent amount of gravity, and a hospitable landscape. Among those, she said the first two are most important, as the atmosphere and magnetosphere could shield colonists from harmful radiation.

Charles Wohlforth and Amanda Hendrix talked about their
new book “Beyond Earth” Nov. 18, 2016 at Town Hall
Seattle. Photo: Greg Scheiderer.

It was easy to winnow the list. Venus was rejected out of hand as a super hot hellhole with a poisonous atmosphere that may well be volcanically active.

“It’s really not the greatest environment for a human settlement,” Hendrix understated, “but what’s interesting about Venus is that in that thick atmosphere there is an altitude at which air that we like to breathe is stable. You could, in theory, have a floating city of balloons that are filled with air and where humans could live.”

On Mercury, Mars, or the Moon people would likely have to live underground to avoid radiation. That’s not very appealing, either.

“It’s not really what we’re going for,” Hendrix said. “We’d like to find a place in the solar system, if possible, where we can live on the ground and have a decent amount of radiation shielding.”

Jupiter has a lot of interesting moons, but the king of planets churns out huge doses of radiation and is not a very hospitable place. When you get out to Saturn, though, Titan catches the eye.

“One of the number-one reasons is that it has an Earth-like atmosphere,” Hendrix said. It’s mostly nitrogen with some methane, and is at about 1.5 times the pressure of our atmosphere on Earth. Titan has no magnetosphere of its own, but for much of its orbit it lies inside Saturn’s magnetosphere, so they can share.

“We think that for our key points of shielding from radiation by either an atmosphere or a magnetosphere, Titan is a very good place,” Hendrix said. “This really sets Titan apart from the other places that we looked at in the solar system for a long-term human colony.”

More positive features

We know a lot about Titan through data gathered on 124 fly-bys of this moon by the Cassini spacecraft. Titan has a lot of Earth-like features. It has clouds, rain, swamps, wind, and sand dunes. It has surface liquid—lakes and seas of methane and ethane. (Water would freeze.) It’s cold there, but Titan has pretty constant temperatures across seasons and latitudes.

There’s also a virtually limitless energy source on Titan. Reactions between its atmosphere, sunlight, and energy from Saturn create hydrocarbons that cover the moon’s surface. Colonists could drill down and get water from Titan’s liquid subsurface ocean, separate out the hydrogen and oxygen, giving them the chemistry needed to burn the hydrocarbons.

“You can imagine settlers on Titan having a power plant that takes in methane and water, and the output is energy and breathable oxygen,” Hendrix said. “So it could work out quite well for our colonists—plenty of energy.”

Don’t pack your bags yet

Setting up a colony on Titan would not exactly be a piece of cake, especially if you didn’t survive the trip. NASA has compiled a long list of potential health risks for astronauts, many of them related to radiation exposure, and concluded that space flights of more than a year are too risky for humans. It would take seven years to get to Titan with current technology.

“These are risks that, without some technology leaps,” Wohlforth cautioned, “we’re not going to Saturn. We simply can’t get there and have the astronauts be safe.”

The key to the trip is finding a way to go faster. Wohlforth said the commercial space sector is making some headway on this, and a NASA scientist named Sonny White is actually working on a propulsion system that uses quantum virtual particles and is also tinkering with a warp drive. That notion drew applause from the Trekkies at the talk, but Wohlforth noted that there’s a pretty good dose of skepticism out there. While warp drive may be “poppycock” as one headline writer opined, it’s not unreasonable to think that some smart engineer is out there cooking up a way to make space ships really zip.

Challenges aside, the urge to go and explore and colonize is strong. Hendrix and Wohlforth touched briefly on a lot of topics that are covered in more depth in the book—such considerations as how society might develop elsewhere, how reproduction might change in a Titan colony, and other challenges and opportunities.

“We really like Titan as a potential human colony location,” Hendrix concluded. “We think it has a lot to offer.”

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Asteroid spotting with NEOWISE

Joe Masiero, a scientist with the
NEOWISE project, spoke at the meeting
 of the Seattle Astronomical Society
Nov. 16, 2016. Photo: Greg Scheiderer.

The solar system seems like a big place with lots of empty space in it, at least until an astronomer plays a simulation of the orbits of its asteroids. Such a simulation looks like an angry swarm of bees, and Earth appears likely to be stung by them several times per day.

Some scientists at NASA’s Jet Propulsion Laboratory convinced the agency a few years ago to give them the keys to a hibernating but still semi-functional space telescope, and now the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) is on the hunt for asteroids and other near-Earth objects. Mission scientist Joe Masiero talked about NEOWISE at this week’s meeting of the Seattle Astronomical Society.
Masiero explained that NEOWISE is a part of NASA’s near earth object observation program.

“This is one of the funding lines that NASA has specifically dedicated to discovering and characterizing objects that come close to the Earth,” he explained. “It’s one of a number of missions and a number of telescopes that do these surveys for near-Earth objects trying to look out to see if anything is posing a hazard to our planet.”

Used scope for sale

That important work is being done by a hand-me-down space telescope. WISE launched in December of 2009 on a mission to essentially build an infrared atlas of stuff to help scientists decide where to point the James Webb Space Telescope when it becomes operational. WISE looked for the most luminous galaxies in the universe, close and cold brown dwarfs, and other sorts of objects for Webb to explore. That mission complete by the following September—and two of four infrared wavelength detectors shot because their coolant ran out—WISE was put into hibernation for almost three years. But the JPL team thought the 40-centimeter scope could still be used for science with the two infrared detectors that didn’t need cooling, and convinced NASA to resurrect WISE as NEOWISE. They fired the scope up again in December of 2013.

“The goals of the NEOWISE mission are to survey near-Earth objects,” Masiero explained, “both to discover new ones, but even more importantly, to characterize ones that we currently know about, to figure out how big they are and how reflective they are, because it’s the reflectivity, the albedo of an object, gives you an initial hint as to what it’s made of.”

There are a number of programs looking for near-Earth objects, such as PanSTARRS and the Catalina Sky Survey, but Masiero said NEOWISE brings something different to the table.

“One of the benefits of NEOWISE as an infrared survey is that we’re discovering a lot of these objects that are very dark—that look like a lump of coal—and sometimes that are very big,” he explained, adding that this is the mission’s special niche.

“There are other surveys finding more near-Earth objects than we are,” he said, “but what we excel at is finding these very dark objects that other telescopes miss.”

The mission has been prolific. Between WISE and NEOWISE, Masiero said they’ve discovered about a thousand near-Earth objects larger than a kilometer.

“Those are the dinosaur-killer level,” he said. In addition, they’ve found about 20,000 objects in the 100-meter class; the type that could cause a “bad day” were they to hit Earth.

Science, too

Possible mass extinction is reason enough to keep an eye out for near-Earth objects, but Masiero notes that there’s science to be done as well. Since these objects are close in they’re easier to study and visit, and there are a number of future missions planned to do just that. Asteroids could also give clues to the formation of the solar system.

Masiero’s particular interest is in looking at main-belt asteroids, which don’t get as much study because they’re so hard to see. One interesting thing they’ve been able to do with NEOWISE is to determine the albedo of asteroids. They’ve found that many objects with a matching albedo also share the same orbital inclination. These asteroid “families” traveling in clusters also often match in optical color.

“This is a single large object that something crashed into and shattered into hundreds or thousands of smaller pieces,” Masiero said. “Because it came from a single object, they all have a similar composition.”

These families are pretty new, geologically speaking. Masiero said that families that formed in the last billion years or so make up over a third of all the objects we know about in the main asteroid belt. NEOWISE data may help scientists track the families, learn what they’re made of, and how they evolved.

The next generation

NEOWISE is funded through next summer, and while they’re hoping to get an extension, eventually the satellite’s orbit will decay and it will burn up in the atmosphere. Masiero said they’re now proposing a new mission, called NEOcam. This would be similar to NEOWISE, except the telescope would be a bit bigger, with a 50-centimeter mirror, and they would fly it out to the first Lagrangian point—L₁—where it would stay cold and work indefinitely.

NEOcam: NASA/JPL-Caltech

“If we’re selected we would fly this space telescope specifically designed to search for near-Earth asteroids in the infrared,” Masiero said. “The goal of this survey is to characterize these objects, quantify them, and help us predict what kind of hazard they could pose to the Earth.”

NEOcam could take longer exposures and thus look deeper into space and find more objects. He expects a five-year survey would find some 300,000 near-Earth objects and eight million main-belt asteroids—an increase of an order of magnitude for both.

“This would improve upon the census taken by NEOWISE, helping us characterize the hazard, but also—very interesting from a scientific point of view—figure out where these populations turn over, how many you have in each size band, and hopefully trace them back to where they come from,” Masiero said.

Citizen science

If you want to sift through the data on your own, it’s all available online. Masiero said it is all on the Infrared Science Archive (IRSA), where there are millions of images and only a few people to look at them. He said the Planetary Data System and NASA’s Horizons tool have also incorporated NEOWISE data.

Perhaps you will spot a killer asteroid or figure out how the solar system formed.

Mapping the heavens with Priya Natarajan

Priyamvada Natarajan, a theoretical astrophysicist at Yale University, is excited to be working in physics and astronomy at a time she and others call the “golden age of cosmology.”
“The maturity of our theoretical understanding, the sophistication of our instruments and tools that allow us to get the data—spacecraft, detectors—and the advanced computing are all aligned at the moment,” Natarajan said this week during a talk at Town Hall Seattle.

Theoretical astrophysicist Priyamvada
Natarajan spoke Nov. 14, 2016 at Town
Hall Seattle.

Natarajan has done a lot of work on mapping dark matter and dark energy, on gravitational lensing, and on figuring out how supermassive black holes are formed. It’s the latter that has her excited for the launch of the James Webb Space Telescope. She’s been a leader in pushing the idea that supermassive black holes could be formed by the direct collapse of matter. The physics pencils out, and Webb will peer back and possibly find the most distant, and therefore the first, black holes, and perhaps validate her ideas.

“The fact that you can come up with an idea as a scientist, for me, that’s the privilege,” she said.

Natarajan is the author of Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos (Yale University Press, 2016). She said she wrote the book not only to help us understand new discoveries about black holes and dark matter, but also to demystify the process of science.

“I believe very strongly that the current rampant disbelief in science stems from the contingent nature, the provisionality of science.” Natarajan said. “It’s something that’s very hard for the public at large to understand.”
The plus side is that cosmology and astronomy have the potential to win converts.

“Unlike many other fields in science, the night sky belongs to all of us,” she said. “We have to just look up and it’s there; the glory and the awe of the night sky.”

We know a lot

Natarajan finds it interesting that we know so much about the universe, with pretty solid evidence for much of what has happened since the tiniest fraction of a second after the Big Bang.

“It still stuns me that with a cantaloupe-sized gelatinous thing in our skull we’ve been able to figure all of this out,” she laughed. Yet despite all we do know, she said there is still a lot of mystery about our peculiar universe.

“We happen to live in one in which the total energy content of the universe is dominated by two components that we don’t know what they are,” she said.

Chart: NASA

What we call them are dark matter, which makes up 24 percent of the universe, and dark energy, which makes up 71 percent. We and all the stuff we see are less than five percent. Though we don’t know what dark matter is, Natarajan said there is solid evidence that it is indeed out there.

“The idea came out of an empirical need to explain an observation,” she said. Oddly enough, one of her other research interests, black holes, were conceived in exactly the opposite fashion.

“Black holes were actually proposed as a mathematical entity,” she noted. “They were a mathematical solution to Einstein’s equations, and they eventually became real.”

A little history

Dark matter was first suggested by Fritz Zwicky in 1933. Vera Rubin and others looking at galaxies in the 1970s proposed it as the reason rapidly spinning galaxies don’t fly apart. Natarajan said more than 80 years of research has left little doubt.

“We have incontrovertible evidence from many independent lines of investigation for the existence of dark matter because of the effects it produces, although it has not been directly detected yet,” she said. “We don’t know the particle.”

There are two lines of evidence, according to Natarajan, that make dark matter far more than just an inference.

“We can exquisitely map it at the moment, even though we can’t see it, because of the gravitational influence that it exerts,” she said. “The other way in which we can detect dark matter is the impact that matter has on the propagation of light in our universe.”

This is where her work on gravitational lensing fits in. Large galaxy clusters, with as many as a thousand galaxies, can act as a sort of gravitational lens on steroids. Such clusters would be held together by enormous amounts of dark matter. The relativity “pothole” created by the cluster could be strong enough to split a beam of light.

“You end up seeing multiple images of an object where in reality there is only one object,” Natarajan said, noting that this has been observed many times now. Interestingly, she points out that the physics of both Newton and of Einstein would predict the effect.

“You can apply both of these arguments to clusters and you infer the same amount of dark matter,” she said. “In my opinion that is really, really strong evidence, compelling evidence, because they’re completely different world views and they still converge. There’s no escaping the concept of dark matter.”

Search for the holy grail

Natarajan said this sort of research may help us get to the holy grail of physics: a quantum theory of gravity.

“The motivation is to look for gaps, look for disagreements, and look for anomalies where an observation is actually inconsistent with our theoretical expectation,” she said.

A couple of great examples of this came out of the 1800s. The orbit of Uranus didn’t agree with Newton’s Laws, so they did the math and figured another planet could cause the observed discrepancies. That led to the discovery of Neptune. At the same time, there were anomalies in Mercury’s orbit, which led to the proposal that another planet, called Vulcan, was the cause. Vulcan was never found, but years later general relativity explained the precession of Mercury’s orbit perfectly.

“In one case the theory remained intact and an anomaly refined our understanding,” Natarajan said. “In the other case it pointed the way to the existence of a more fundamental covering theory that was yet to come.”

We can’t wait for the next breakthroughs in this golden age of cosmology.

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Book review: Chasing Venus

Like many astronomy buffs, we’ve been putting a great deal of thought into deciding where we’ll go to try to see the total solar eclipse that will cross the United States next August 21. Seattle Astronomy has done 13 articles and a dozen podcasts on the topic. As with the 2012 Venus Transit or this year’s Mercury Transit, the key is figuring out where you’ll have the best odds for clear skies, and how to get to an alternate site if the clouds beat those odds on eclipse day.

With such thinking fresh in mind, I eagerly snapped up a copy of Andrea Wulf’s book Chasing Venus: The Race to Measure the Heavens (Vintage Books, 2012) when I spotted it in the astronomy section of Powell’s Books during a recent trip to Portland.

Chasing Venus is the story of the Venus transits of 1761 and 1769, and the international scientific effort to accurately observe the transit from many spots around the globe and use the solar parallax between those observations to calculate the distance between the Sun and the Earth, and thus get a true grasp for the size of the solar system.

The whole project was the brainchild of British astronomer Edmund Halley, who predicted the 1761 transit and wrote an essay in 1716 that urged scientists to spread out across the globe to make these vital observations. Halley was 60 at the time of the writing and would have to live to be 104 to see it himself; he died in 1742.

Scientists and nations answered the call with enthusiasm. This was, Wulf writes, “a century in which science was worshipped, and myth at last conquered by rational thought.” One is tempted to think that we’ve regressed in the intervening 247 years.

Technology was a challenge for the observers. They had good telescopes, but had to transport them long distances, in many cases, and set up observatories in remote locations. A bigger challenge was the actual timing of the transit. Clocks were not yet reliably accurate, and precise determination of longitude was still a challenge. The greater difficulty was actually getting to the observation sites. It was easy for those in the cities, but for the calculations to work observations had to be made from points on Earth as far apart as possible. Thus for every astronomer observing from the relative comfort of Paris, London, or Madrid another team was on a treacherous expedition to the far-flung corners of the world in an era when it took several months to get a letter from the American colonies to the European capitals. For the 1761 transit, the journey of French astronomer Jean-Baptiste Chappe d’Auteroche to Siberia was particularly harrowing, and those traveling by sea had to navigate not only the sea but the politics of the day, lest their efforts be defeated by heavy waters or hostile navies.

Imagine the mindset of astronomers who, at great expense, had to travel for months, and in many cases more than a year, in order to set up and prepare for an event that, if it was cloudy during the wrong six hours, would be a total bust. It makes our deliberations about where to go to see the 2017 total solar eclipse seem trivial by comparison.

Measurements of the first transit proved largely unsuccessful. Weather foiled many of the expeditions, and a variety of problems caused great variance in the accuracy of the data collected. But they learned from the effort and improved their approaches, and by the time of the 1769 transit, the combined observations narrowed down the distance to the Sun to within four million miles, which was quite an improvement.

Wulf spins a great tale of scientific inquiry, daring (and not-so-daring) adventurers, political intrigue, and fascinating personalities involved in what was arguably the biggest collaborative international scientific event up to that time. It’s a marvelous read and highly recommended.

Special cookies and two books about next year's total solar eclipse

I’ve recently read two fantastic books about the total solar eclipse that will sweep across the United States on August 21, 2017. One is geared toward kids, while the other could be a useful tool for serious adult eclipse chasers.

The Big Eclipse (Orbit Oregon, 2016), written and illustrated by Nancy Coffelt, is a beautifully done 16-page book that children will love and easily understand. It’s a lighthearted and playful eclipse primer that explains what will happen and how to watch it safely, looks at odd effects of eclipses, shows how to make a pinhole projector, and has a glossary with meanings for all of those new words like totality and umbraphile. While aimed at children the book is not dumbed down, and it’s certified “astronomically accurate” by an eclipse expert at the American Astronomical Society.

Sold separately is The Big Eclipse Activity Book that supplements The Big Eclipse. It is packed with games, puzzles, art and imagination projects, and even has a recipe for “eclipse cookies” that you can make and serve at your total eclipse viewing party. It would be great for school projects, family fun and learning, or just for a kid who loves to read and figure things out solo. Grab both volumes; they’re perfect for kids around ages five to eleven.

We did an earlier article and podcast with Michael Zeiler, who along with his wife Polly White operates the dandy eclipse website GreatAmericanEclipse.com. Zeiler also has come out with a book, a compact 44-pager titled simply See the Great American Eclipse of August 21, 2017 (Great American Eclipse LLC, 2016). The book is packed with maps and information, touching on the splendor and science of the event, safe viewing, best places to see the eclipse, strategies for success, and lots more maps. It’s super informative, and small enough to slip into your satchel or even a larger pocket and head out for some eclipse chasing.
As discussed in the podcast, Zeiler works hard to make his maps not only accurate and informative but visually pleasing. He dose marvelous work, and he has a selection of poster-size maps suitable for framing on the website.

Safety tools are included with both books. The Big Eclipse comes with a rectangular solar viewer, while a copy of See the Great American Eclipse will also get you a couple of pairs of eclipse glasses.

You can snag all three books by visiting the links above. Buying through Seattle Astronomy helps us defray the costs of bringing you great space and astronomy articles, and we thank you for that.
There’s more info and additional eclipse swag on the websites for Orbit Oregon and The Great American Eclipse.

LSST: mining the sky in 4D

The Large Synoptic Survey Telescope (LSST) is going to be a unique astronomical instrument.
“Unlike a lot of other telescopes around the world, LSST is actually aptly named,” joked Dr. David Reiss of the University of Washington at a recent gathering of Astronomy on Tap Seattle at Peddler Brewing Company in Ballard. Reiss and Dr. John Parejko, two UW astronomers involved in the project, gave an overview of the telescope, which is under construction in Chile.

John Parejko (left) and David Reiss, research scientists at the
University of Washington, discussed the Large Synoptic Survey
Telescope at an Astronomy on Tap Seattle event October 28 at
Peddler Brewing Company in Ballard. Photo: Greg Scheiderer.

As for the name, Parejko noted the scope will be truly large. It will have an 8.4-meter mirror, a 3.2-gigapixel camera, and will take an image of the night sky every 30 seconds.

“We’re going to generate 15 terabytes of data every single night,” Parejko noted. “That means by the end of the survey we’ll have 30 trillion database entries, and over half an exabyte of data and images being catalogued.”

“That’s a lot of data even for those of you who work at Amazon,” he quipped.

Synoptic is the word even the scientists say they have to look up every time. Essentially it means that the instrument will look at everything as a whole and provide a synopsis.

“Unlike a lot of other telescopes, the LSST has been designed to serve thousands of astronomers with interests ranging from supernovae or exploding stars, to planets and asteroids, to the universe as a whole,” Reiss explained.

It’s a survey because LSST will not look at just one object.

“Not only is it covering all kids of different science, it’s actually covering the whole sky,” Parejko said. They hope to start observing in 2022, and the 10-year survey will photograph the entire sky every three nights. They expect to discover 37 billion stars and galaxies.

Lastly, it’s a telescope, but it’s much more.

“The main thing that LSST is going to produce is lots and lots of data,” Reiss said, “images and catalogs and databases of all of the objects in the sky that are going to be shared with everybody in real time.” With new information coming in constantly, they’ll be effectively creating a 10-year, multi-color, ultra high-resolution movie of the night sky.

The building

Parejko described the facility, which is being built on the Cerro Pachón ridge at 8,700 feet elevation, not far from town of La Serena in the mountain desert of Chile. It’s a good site for an observatory, with high elevation and low humidity. The building has been designed with a lab for working on the mirror and other parts of the telescope so that they don’t have to send things off the mountain for repairs.

“That means we minimize our down time; we can spend as much time as possible taking data,” Parejko said. You can watch progress of the construction on the LSST webcam.

An artists’ concept of the Large Synoptic Survey Telescope.
Image: LSST.

The telescope itself will be short, squat, and compact, with the secondary mirror and camera located out at the end. They’re building it short to reduce wobble when it moves—another measure for minimizing down time. They were able to keep it short by using a different shape on the outside of the primary mirror than on the inside. Light will come into the scope, reflect off the outside of the primary to the secondary mirror, back down to the inside of the primary, which will beam it up to the camera.

“That’s how we can keep the telescope so short and compact, by folding the light like that,” Parejko explained.

The camera, about the size of a Smart Car, will have three lenses and space for five filters. The detector will feature 21 “rafts” each with nine CCDs. If one raft breaks, they’ll just pull it out, plug in another, and keep imaging.

The building will also include a major computer lab. That’s still under design.

LSST software

Reiss explained that, with so much data being collected, computing will be important. Essentially, they’re building, “sort of a Google index of the entire night sky over the course of ten years.” To do that, they’re creating a high-speed network to connect the telescope in Chile to a supercomputing center in Illinois. There, they’ll look for things that move or blow up, and expect to spot some 10 million events every night. Information about these discoveries will go out in nightly alerts to interested users.

“We’re basically providing the equivalent of astronomical Twitter, Google, and Amazon Web Services to the community,” Reiss said.

“We’re going to be sending out nearly 600 gigabytes worth of simply just these alerts every night,” he added. “If one of you were going to subscribe to these you’re going to max out your Comcast monthly allocation in one night.”

Researchers will be able to upload their software or algorithms into the LSST computing cluster and do calculations in the cloud, rather than having to download all of that data. Many institutions will receive the alerts and write algorithms that will help users pick and choose data. There will likely be smartphone apps that will allow users to, say, track their favorite asteroid, and people will be able to use the data to learn about the universe or do citizen science. Reiss noted that, by keeping a constant eye on the sky, we will be able to spot lots of the sorts of things that we only find today through the luck of looking in the right place at the right time.

LSST goals

The main science goals of the LSST are to learn about dark matter and dark energy, catalog the solar system, watch how things change, and learn about the structure and formation of the Milky Way.

The LSST team includes 39 institutional members, among them 21 colleges and universities. The UW is a founding member. The project employs 200 astronomers and engineers from 19 different countries. The total cost of getting LSST up and running by 2022 will be about $400 million. That sounds like a lot of money, but Reiss and Parejko pointed out, given the season, that it’s about what Americans spend on Halloween costumes for their pets in a typical year. Funding for the project has come from the National Science Foundation, the U.S. Department of Energy, and through fundraising by the nonprofit LSST Corporation.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. The events are free, but you can help them cover the costs of creating them by donating online to the Friends of Astronomy Fund at the UW.

LIGO founder Rainer Weiss talks gravitational waves at UW

There has been a great deal of talk about gravitational waves since scientists with the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced back in February that they had collected the first evidence of the phenomenon in September 2015. Dr. Rainer Weiss, professor emeritus of physics at MIT and one of the founders of LIGO, talked about the history, discovery, and future of LIGO Tuesday at the University of Washington. The event was part of the Frontiers of Physics lecture series of the University’s College of Arts and Sciences.

Was LIGO really the first?

Dr. Rainer Weiss, a co-founder of LIGO, gave a lecture this
week at the University of Washington about the detection
of gravitational waves. The logos represent the more
than 80 organizations involved in the LIGO
Scientific Collaboration. Photo: Greg Scheiderer.

Weiss said that it might not be totally accurate to say that LIGO was the first to spot gravitational waves. Joseph Weber at the University of Maryland claimed to have detected them way back in 1969, but no other scientists could duplicate his observation, and the claim was eventually discredited. Weiss said much credit should go to Russell Hulse and Joseph Taylor, Jr., of the University of Massachusetts. They used a radio telescope to study what is now called the Hulse–Taylor binary, and noticed that the orbits of these two neutron stars around each other have decayed since they were discovered in 1973. A graph of the decay matches up precisely with a plot of the loss of energy predicted due to gravitational waves.

“It’s a dead ringer,” Weiss said. “That was, as far as I’m concerned, the first real evidence that there were gravitational waves. It was a very important moment, because there had been endless discussions in the scientific community about whether the gravitational waves that Einstein had predicted were real or not.”

In a way the detection of gravitational waves is like the story of an “overnight sensation” who hits the big-time after decades toiling in obscurity. The first glimmerings of LIGO go back more than 40 years, and the basic design of the observatory was actually created well before Einstein dreamed up gravitational waves as part of the general theory of relativity.

The beginnings of LIGO

Back in 1967 MIT asked Weiss to teach a course about relativity. He didn’t tell them that he wasn’t really up on the math of relativity, and joked that it was all he could do to keep a day ahead of his students. Weber was doing his experiments at the time, and Weiss had his class do a thought experiment—what Einstein would call a Gendankenexperiment—about how to detect gravitational waves using light beams. Their solution was essentially a Michaelson Interferometer, a device developed in 1880s. (An animated view of a simple interferometer is below; also check our recent post about LIGO from an Astronomy on Tap Seattle event.) A few years later, after the Weber findings were dismissed, Weiss started to think about the detection of gravitational waves a little more seriously.

“I wanted to convert that Gedankenexperiment into a real apparatus,” he said.

An animation of how LIGO works. A laser beam is directed through a splitter into two
equal-length arms, and reflected back. If the length remains the same, the reflected beams
cancel each other out. But if a gravitational wave distorts the beams, they do not cancel and
light reaches a detector. Image credit: LIGO/T. Pyle.

This was easier said than done. As noted, many in the scientific community doubted that gravitational waves existed, and even Einstein had expressed doubt that they could ever be detected. This made getting funding for the work a challenge. The technical obstacles were greater still. The device had to detect preposterously small distortions in spacetime—along the order of a thousandth of the width of a proton—and it had to do so in an environment in which there is a tremendous amount of noise. The Earth itself is spinning and vibrating, ocean waves lap up on the shore, a train goes by. They had to figure out a way to get the interferometer mirrors to hold still. That problem was solved by suspending the mirrors from multiple pendula, which themselves hang from a noise-reducing feedback system. Even a little heat or a molecule of oxygen in the interferometer tube could distort the light beam.

“The way you get rid of it: you make a very good vacuum, and that costs a lot of money,” Weiss noted. They also added mirrors to the basic design that make the light path longer and keep more light in the system, both ways to amp up the sensitivity of the instrument.

It’s no wonder this “overnight” discovery was more than 40 years in the making, and didn’t happen until a century after Einstein first proposed gravitational waves. Weiss spent a lot of time recognizing the many scientists who contributed to LIGO over the years, and noted that today the LIGO Scientific Collaboration includes more than one thousand people from 83 different organizations.

More discovery to come

The future of gravitational wave astronomy is fascinating, according to Weiss. With the VIRGO interferometer in Italy and LIGO-India (INDIGO) joining the LIGO facilities at Hanford, Washington and Livingston, Louisiana, scientists will be able to triangulate to get a better idea about where detected gravitational waves originate. The eLISA mission of the European Space Agency would be a huge interferometer in space that could possibly spot gravitational waves with longer lengths, created by such events as the mergers of supermassive black holes. The LISA Pathfinder mission successfully tested some of the technology earlier this year, and the ESA just this week put out a call for concepts for the next phase of the project. Most interesting is the possibility to detect gravitational waves from almost the instant of the Big Bang, which could be spotted as density variations in the cosmic microwave background.

“I fully expect that if there are gravitational waves that come from inflation, in the next ten years they’ll be found,” Weiss predicted.

A full house at the UW enjoyed the engaging lecture by Weiss.